What has changed?

1 second 2 seconds 3 seconds 4 seconds 5 seconds 6 seconds 7 seconds 8 seconds 9 seconds 10 seconds 11 seconds 12 seconds 13 seconds 14 seconds 15 seconds 20 seconds delay, loading photo...          Just downstream of the previous pair of Amersham photographs in 1999  Author: Chiltern Society,          Weeds had taken over the riverbed in 1997  Author: Chiltern Society,